The Visual Analogue Scale Versus Numerical Rating Scale in Measuring Pain Severity and Predicting Disability in Low Back Pain

BACKGROUND: Low back pain (LBP) is a public health problem that requires accurate assessment for proper management and predicting prognosis. OBJECTIVE: This study aims to assess the agreement between visual analogue scale (VAS) and numeric rating scale (NRS) in measuring LBP severity, and investigate their ability in predicting disability. METHODS: A cross-sectional study was performed on 100 patients with chronic LBP. Pain severity assessment was performed using VAS, NRS, and pain severity scores of the Brief Pain Inventory (BPI). Disability assessment was done by BPI-Pain interference and Modified Oswestry Disability Index (MODI). RESULTS: There was a significant positive correlation between VAS and NRS (r = 0.92, p < 0.001) with high agreement between both as detected by Bland-Altman method (mean difference = 0.33). Moreover, there was significant (p < 0.001) positive correlation between disability scores and either VAS (r = 0.92 with BPI pain interference; r = 0.75 with MODI) or NRS (r = 0.95 with BPI pain interference; r = 0.68 with MODI). By using receiver operating characteristic curve, a score of 6 in VAS or NRS can predict severe disability, whereas VAS score higher than 4 and NRS score higher than 3 can predict moderate disability. CONCLUSIONS: Visual analogue scale and NRS appeared reliable in assessing LBP severity with no significant difference between them. Moreover, either VAS or NRS scores can predict disability of patients with LBP.